meta-singleton_classes.rb

#!/usr/bin/env ruby

class Parent

  class << self

    def greet
      "singleton parent"
    end

    class << self

      def greet
        "meta-singleton parent"
      end

      # if the method were not defined above, the call would not propagate up
      # the singleton class chain as there IS no singleton class
      # chain in the context of belonging to the same singleton object.
      #
      # In effect, this makes singleton method lookup parallel and really
      # nice and easy

      class << self

        def greet
          "meta-meta-singleton parent"
        end

      end

    end

  end

end

class Child < Parent

end

p Child.greet
p Child.singleton_class.greet #see line 17
p Child.singleton_class.singleton_class.greet

p Parent.singleton_methods
p Parent.singleton_class.singleton_methods
p Parent.singleton_class.singleton_class.singleton_methods